Modern aircraft typically include a great number of sensors, effectors (e.g. actuators), etc., connected to an avionics network having one or more central processors in an avionics bay. The sensors, effectors, etc. are typically concentrated at particular locations in the aircraft where systems are installed. To reduce wiring, and therefore weight, a remote data concentrator (RDC) may be used to connect several of the sensors, effectors, etc. to the central processors via data buses.
RDCs and avionics bay units are examples of LRUs commonly found in avionics architectures. To reduce design and manufacturing costs, and to improve operational effectiveness, the LRUs may be standardised. For example, the RDCs on a particular aircraft may have common hardware, regardless of the sensors, effectors, etc. to which they are connected, and so are known as common remote data concentrators (cRDCs). The cRDCs may include configurable software. Standardisation of the LRUs makes it possible to hold an inventory of fewer parts, such that a defective LRU can be readily replaced during routine maintenance tasks, thereby improving operational effectiveness.
Each wire route within an avionics architecture may carry a route designation, and route segregation rules are typically applied to architecture design. The route designation may be, for example, a side of an aircraft and/or a level of “essentiality”. Wire routes are typically bundled on either side of the aircraft (side 1 or side 2) such that a single side failure does not affect the other. The essentiality is a measure of criticality and reliability within the avionics architecture. The wire route segregation rules may, for example, call for segregation of wire routes on either side of the aircraft and/or of wire routes of different essentiality. The wire route segregation rules may call for segregation up to and including the connectors, which connect the wire routes to the LRUs.
Whilst the provision of common LRUs within the avionics architecture provides several advantages as mentioned above, the number of wire routes of a particular route designation can be variable across the aircraft. This, together with wire route segregation rules makes it difficult to introduce a common LRU design without providing the LRU with a larger number of interface hardware than there are wire routes to be connected at most locations. Unused interface hardware has an associated component cost, space and weight penalty, which is undesirable as it reduces operational efficiency, e.g. increased fuel burn.
One existing solution for reducing the amount of unused hardware in commonly designed LRUs calls for an integration panel between the connectors and the LRU. The integration panel carries a short length of mixed wire route bundles so as to increase the number of instances where most of the LRU interface hardware is in use. This solution is used commonly on avionics bay LRUs. However, the integration panel carries a weight and space penalty.
Another existing solution is to provide the commonly designed LRUs with a reduced number of hardware interfaces, and to increase the number of LRUs at specific locations where the number of hardware interfaces available is insufficient, rather than provide bespoke designed units at those use intensive locations. Duplication of LRUs carries a weight and space penalty.